This license is for a maximum of 3 Dual-CPU servers & vCenter Server for Essentials. Support and subscription listed is for 1 year. Production (Prod): 24 Hours/Day 7 Days/Week 365 Days/Year; Basic (B):12 Hours/Day Monday-Friday.
The Essential kits are self-contained solutions and may not be decoupled or combined with other VMware vSphere editions. There are upgrade options available if needed.
Details here: http://www.vmware.com/files/pdf/vsphere_pricing.pdf
http://www.vmware.com/products/datacenter-virtualization/vsphere/pricing.html